DIY LTCC or similar system for LT1s

[spfautsch]

... that capacitor is not between controller and resistor{AS per PCM design}, but is between resistor and coil. Do you think it will make any difference.

Without knowing the type of outputs the ICs in the PCM use along with the size of the caps it's hard to know what they were trying to accomplish there. Am I correct to assume that is an ASIC (i.e. made to order for a specific application)? Whatever the case, this is why I asked for testers, not customers wanting to buy a turn-key complete product, which this is not. With that said, I haven't noticed any controller resets while running with this RC network configuration so I'm working on the assumption they're doing their job adequately.

Also the temp compensation is tied with voltage, so in the end there is 3d matrix of adjustments. If it was so unimportant I doubt GM will make an effort to dial those tables.

I left this at "I'm going to look into the possibility" (of adding temperature compensation). No idea where you're getting the idea that I don't think it's important. I just don't think it makes sense to blindly emulate the factory tables when there are so many variables (most notably coil mounting location). For example, though I'm only vaguely familiar with the LS1/2/3/6 engines, weren't all the coil packs mounted directly on the (aluminum) valve covers? Didn't they also mostly have "dress-up" covers? All this can and does affect coil operating temperature. The coil mounting options on gen 2 LT-1s are much different and can be a matter of personal choice. All these variables need to be taken into consideration. To be thorough about it, one would have to mount temperature sensors on the coil packs and run the vehicle. I don't quite have the time or the R&D budget to accomplish that, much less willing test candidates. Which is why I've somewhat left the project at the "it's working for me" state. Though I'd like to, this is one of the primary reasons why I'm not trying to make money with it - the money I've taken in hasn't scratched the surface of my costs for the materials, not to mention the time spent ordering, counting out the parts, packaging, defective out-of-the-package AVRs, etc.

I am not a fan of `kind of worked` approach or it will work only at room temperature approach. It either gets done the right way or goes underground.

Then perhaps this isn't something you would want to participate in. I hope you've read the comment header previously, but if not, and to make it clear for readers new to the thread.

From the source .ino file (it's written in c++):

////////////////////////////////////////////////////////////////////////////////////////////////////////////////
//
//  this code is to be considered experimental and is provided "as is", without warranty of any kind,
//  expressed or implied, including but not limited to fitness for a particular purpose.
//  if your LT1 comes apart using it i will not be held responsible
//  you were warned

Now I need a firmware for SPFcop

The name of the project was taken from the title of this thread. It's silk-screened on the PCB. It's quite certainly not "SPFcop". I just don't want you referring to it as LTCC which is Bob Bailey's product. Both for copyright concerns, and to prevent readers from being confused as to what we're talking about. Over the last year or so I've simply been calling it "the controller" because it's the subject of the thread.

... that runs dual mode based on rpm threshold. All the time it will calculate dwell as needed but on lower rpms based on threshold it will run as sequencer. I think it will be a piece of cake to add sequencer mode with a rpm switch on top of the existing code.

Since (I assume) it would require a patch for the PCM, I would consider that a possible option for startup dwell if, and only if temperature compensation within the controller is not feasible. I won't be able to investigate that for at least a couple weeks, best case.

I'm really hoping to have time this weekend to get some preliminary test data on the coils across a reasonable temperature spectrum. I have a cheapo toaster oven and a nice industrial process heater controller ready to be combined into a semi-lab worthy piece of equipment.

Too bad you have a manual and can`t test a downshift.

This is a typical downshift into my favorite hard left corner. It's nowhere near as abrupt as an automatic, but I think you'll find the overrun clutch hub in the 4l60e will only handle a limited amount of abuse like that before it fractures.



Next time I have a chance and traffic allows it I'll try a downshift to 2nd which should get the revs a lot higher. Whatever the case I'm not going to let the chassis do all the work because going from 5th to 2nd without rev matching will certainly break the tires loose, not to mention beating the hell out of the driveline.

Edit: It occurred to me after re-reading this that you were talking about a throttle kickdown type downshift. This is the kind of thing that makes me cringe because I know it's really hard on the trans, and rebuilding autos is a messy pain in the backside.